The purpose of the present investigation was to test the hypotheses that the mechanomyographic (MMG) signal would be affected by hydration status due to changes in the intra- and extracellular fluid content (which could affect the degree of fluid turbulence), changes in the filtering properties of the tissues between the MMG sensor and muscle, and changes in torque production that may accompany dehydration. Ten subjects (age 22.5 +/- 1.6 years) were tested for maximal isometric (MVC), submaximal isometric (25, 50, and 75%MVC), and maximal concentric isokinetic muscle strength of the biceps brachii in either a euhydrated or dehydrated state while the electromyographic (EMG) and MMG signals were recorded. Separate three-way and two-way ANOVAs indicated no change in torque, EMG amplitude, EMG mean power frequency (MPF), MMG amplitude, and MMG MPF with dehydration. The lack of dehydration effect suggests that MMG may be more reflective of the intrinsic contractile processes of a muscle fiber (torque production) or the motor control mechanisms (reflected by the EMG) than the tissues and fluids surrounding the muscle fiber.

It has been suggested that Eleutherococcus senticosus (ES), also known as Siberian ginseng or ciwuija, increases fat utilization in humans. The purpose of this study was to examine the physiological responses to supplementation with ES in endurance cyclists. Using a randomized, double-blind crossover design, 9 highly-trained men (28 +/- 2 years, VáO2max 57.3 +/- 2.0 ml á kg-1 á min-1) cycled for 120 min at '60% VáO2max followed by a simulated 10-km time trial. Diet was controlled, and ES (1,200 mg á day-1) or a placebo (P) were administered for 7 days prior to each of the two trials. Oxygen consumption, respiratory exchange ratio, and heart rate were recorded every 30 min, and rating of perceived exertion, plasma [lactate], and plasma [glucose] were recorded every 20 min during the 120 min of steady state cycling. There were no significant differences (p >.05) between the ES and P groups at any steady-state time interval or during the cycling time trial (ES = 18.10 +/- 0.42, P = 17.83 +/- 0.47 min). In contrast with previous reports, the results of this study suggest that ES supplementation does not alter steady-state substrate utilization or 10-km cycling performance time.

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